Use pipe to main process instead of printing directly from the signal handler to avoid futex wait blocking

Signed-off-by: DL6ER <dl6er@dl6er.de>

src/dnsmasq/dnsmasq.c

@@ -1310,7 +1310,10 @@ int main_dnsmasq (int argc, char **argv)
 
 static void sig_handler(int sig)
 {
-  log_debug(DEBUG_ANY, "dnsmasq received signal %d", sig);
+  /**** Pi-hole modification ****/
+  send_event(pipewrite, EVENT_SIGNAL, sig, NULL);
+  /******************************/
+
   if (pid == 0)
     {
       /* ignore anything other than TERM during startup
@@ -1570,6 +1573,12 @@ static void async_event(int pipe, time_t now)
 	my_syslog(LOG_WARNING, _("script process exited with status %d"), ev.data);
 	break;
 
+  /**** Pi-hole modification ****/
+      case EVENT_SIGNAL:
+	log_debug(DEBUG_ANY, "dnsmasq received signal %d", ev.data);
+	break;
+  /**************************** */
+
       case EVENT_EXEC_ERR:
 	my_syslog(LOG_ERR, _("failed to execute %s: %s"), 
 		  daemon->lease_change_command, strerror(ev.data));

src/dnsmasq/dnsmasq.h

@@ -200,6 +200,9 @@ struct event_desc {
 #define EVENT_SCRIPT_LOG 25
 #define EVENT_TIME       26
 
+// Pi-hole
+#define EVENT_SIGNAL     255
+
 /* Exit codes. */
 #define EC_GOOD        0
 #define EC_BADCONF     1